Debt Debt Fair Value Disclosure (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Long-term Debt, Gross	$ 2,473,927	$ 2,381,929
Long-term Debt	2,473,927
Debt Instrument, Unamortized Discount	(462,274)	(422,681)
3.75% Convertible Senior Subordinated Notes Due 2042 [Member]
Long-term Debt, Gross	390,000	0
Long-term Debt, Fair Value	397,100	0
Long-term Debt	229,624	0
Debt Instrument, Unamortized Discount	160,376	0
7.75% Senior Subordinated Notes, Due 2020 [Member]
Long-term Debt, Gross	550,000	550,000
Long-term Debt, Fair Value	614,600	591,300
3.75% Convertible Senior Subordinated Notes, due 2025 [Member]
Long-term Debt, Gross	318,054	575,000
Long-term Debt, Fair Value	459,600	816,500
Long-term Debt	204,608	361,345
Debt Instrument, Unamortized Discount	113,446	213,655
Convertible Subordinated Debt [Member]
Long-term Debt, Gross		575,000
Junior Subordinated Debt [Member]
Long-term Debt, Gross		345,000
Long-term Debt, Fair Value	331,600	318,800
Long-term Debt	206,266	203,675
Debt Instrument, Unamortized Discount	138,734	141,325
3.25% Convertible Senior Debentures, Due 2035 [Member]
Long-term Debt, Gross	427,500	452,500
Long-term Debt, Fair Value	425,400	404,600
Long-term Debt	377,782	384,799
Debt Instrument, Unamortized Discount	$ 49,718	$ 67,701